FR2618792A1 - POLYMERIC ADDITIVES BASED ON VINYL ETHYLENE / VINYL ACETATE COPOLYMERS FOR IMPROVING THE FLUIDITY OF MEDIUM DISTILLATES - Google Patents

Abstract

The invention relates to polymeric fluidity improving additives for middle distillates based on grafted ethylene / vinyl acetate copolymers as a component of a solvent system, with use as a fluidity enhancing agent. , PFP graft polymers consisting of: a) 20-80% by weight of esters of methacrylic acid and C8-C1 5 alkanols, and b) 80-20% by weight of ethylene / acetate copolymers of vinyl, the viscosity of the ungrafted ethylene / vinyl acetate copolymers eta spec / c (measured at 25 degree (s) C in xylene) being between 6 and 50 ml / g and the degree of branching being between 3 and 15 CH3 groups per 100 CH2 groups, in an LM solvent having a boiling point of at least 50 degree (s) C under a pressure of 1.02 bar.

Description

The invention relates to polymeric additives for the improvement of the

fluidity of middle distillates, &

  base of grafted ethylene / vinyl acetate copolymers.

  The technique increasingly needs to exploit crude oils that have relatively poor flow characteristics or a

  high freezing. As a general rule, these characteristics

  The results are based on the paraffin content, which also has a favorable effect on the adjustment of a good viscosity-temperature behavior of products made from these oils (see Ullmanns Encyklopadie der Technischen Chemie, 4th edition, volume 20). 548, Verlag Chemie, Weinheim, 1981). The treatment of crude oils in refineries results in different product groups that may differ depending on the nature of the crude oil processed and the type of refinery. Essentially, a distinction is made between fractions that boil below about 200 ° C (gasoline), the next higher fraction, boiling up to about 250 ° C (kerosene / kerosene), and as a result of this , the diesel passing up to 350'C approximately. The fractions that pass through the gasoline, that is to say, kerosene and diesel, are usually combined under the name of "middle distillates" in the operation of the refineries (see Ullmanns Encyclopadie der Technischen Chemie). , 4th edition, volume 10, pp. 643-648, Kirk-Othmer, Encyclopedia

  of Chemical-Technology, 3rd ed. flight. 17, pp. 257-271).

  The solution that immediately comes to mind with lubricating oil fractions, namely the removal of some of the paraffins by solvent extraction at low temperatures, weighs heavily on the costs, especially because of the consumption. energy, because the solvents must be recovered and the extraction must be carried out under cooling. Added to this are the difficulties in eliminating paraffin waxes. This is why the technique quickly turned to the search for appropriate additives which guarantee better flow characteristics and a lowering of the freezing point of mineral oils and mineral oil fractions,

particular of middle distillates.

  Copolymers of ethylene and vinyl esters of C 1 -C 6 carboxylic acids, in particular vinyl acetate, having vinyl ester contents of 15 to 40% by weight, have been found to be effective additives for the preparation of vinyl esters. improvement of the fluidity of crude oils and

  middle distillates (EVA copolymers, see GB-C 900 202, US Pat.

  A 3,567,639, US-A 3,048,479). When small amounts are added, only EVA copolymers with relatively low molecular weights between 500 and 5000 and, in particular, having a defined degree of branching show appreciable activity in middle distillates (GBC 900 202, DE-A 19, 14756). Low molecular weight ethylene / vinyl acetate copolymers are claimed in EP-A-0 099 646. Terpolymerization with iso-olefins results in defined degrees of branching of 5 to 15 CH 3 groups per 100 CH 2 groups. According to EP-A 0 184 048, terpolymers of ethylene containing 30 to 45% by weight of vinyl acetate and having an isobutylene content which corresponds to a degree of branching of 2 to about 15 CH 3 groups. per 100 CH 2 groups, with an average molecular weight of about 400 to 1200, are known as pour point depressants. DE-A 36 16 056 relates to the use of terpolymers of ethylene as additives for mineral oils and mineral oil distillates, terpolymers which contain, in addition to ethylene, 0.5 to 20% by weight of diisobutylene. and 20% by weight of vinyl acetate, with a molar mass of 500 to 10,000 g mol. In EP-A 0 196 217, it is indicated a fuel-distillate having a cold filter plugging point ("cold filter plugging point") and a pour point ("for point") improved, which contains , apart from the distillate, 10 to 2500 parts of a terpolymer of ethylene, unsaturated ester and substituted olefin per million parts of distillate. As olefins, it is mentioned diisobutylene, triisobutylene, tetraisobutylene or

mixtures thereof.

  JP-A 53 593/84 (application no. 164 534/82) proposes additives for improving the low temperature fluidity of mineral oils, which are obtained by grafting C 3 -C 21 alkyl esters of (meth) acrylic acid, vinyl esters or optionally substituted styrene. ethylene / vinyl acetate copolymers. In this case, the ethylene content of the polymers is 50-90% by weight and the intrinsic viscosity in benzene at 30 ° C is between 0.08 and 0.5 dl / Sg. The proportion of grafted components should be 20 to 300% by weight based on the EVA copolymer. According to patent FR-A-2,572,410, graft copolymers are known that serve as additives for preventing paraffin deposits and for improving the flow properties of crude oils, copolynmers which consist, for 5 to 95% by weight, by a base polymer of ethylene and at least one unsaturated monomer selected from the group of C 2 -C 18 vinyl esters, C 1 -C 2 alkyl esters of unsaturated monocarboxylic acids, or dicarboxylic acids, , 3-unsaturates or their esters or anhydrides, polymer on which are grafted homo- or copolymers of α-monounsaturated monocarboxylic acid esters with a radical

  alcohol having at least 12 carbon atoms.

  However, the additives of the state of the art can not satisfy every point of view. In particular, there is a need for additives for improving fluidity, which fulfill this role effectively and with a high degree of safety with respect to provenances and specific fractions of the oils. Experience in the art teaches that any combination of ethylene / vinyl acetate copolymers and alkyl methacrylates is in no way able to meet the requirements of the art. On the contrary, it is important to choose and

  prepare, specifically appropriate combinations.

  In the context of the present invention, the interest is concentrated mainly on middle distillates, that is to say on fractions which ordinarily comprise the gas boiling range 170-350 ° C., in particular 225-350 ° C. 'C, actual boiling point according to ASTM D 2892), diesel fuels, turbofuels and

the fuels.

  These include, in general, fractions whose boiling range is above 170.degree. C., preferably above 225.degree. Vinnacker-Kichler, 4th edition, volume 5, Carl Hanser Verlag, Munich, Vienna

nineteen eighty one).

  It has been discovered that the additives according to the invention for the improvement of fluidity fill to an unexpected extent the requirements of the art. The additives according to the invention for improving the fluidity, based on graft polymers of alkyl polymethacrylates on ethylene / vinyl ester copolymers as a component of a solvent system, contain, as an agent for improvement of the fluidity of the PFP graft polymers consisting of: a) 20-80% by weight of alkyl methacrylate containing 8 carbon atoms in the alkyl radical of the ester, and b) 80-20% by weight of ethylene / vinyl acetate copolymer, preferably with 28-40% by weight of vinyl acetate, the initial viscosity of the ethylene / vinyl acetate copolymers q spec / c (at 25 ° C. in xylene) being included preferably between 6 and 50, in particular between 6 and 30 ml / g and the degree of branching being between 3 and 15 CH 3 groups per 100 CH 2 groups, in an LM solvent having a boiling point of at least 50 ' C and preferably> 100 ° C under a pressure of 1.02 bar <760 mm) . As a general rule, (a) and (b) complement each other

% in weight.

  Solvent LX is inert with regard to radical reactions and is preferably selected from the group consisting of hydrocarbons or cetane number improvers (CNI improvers), particularly in the group of alkyl nitrates. and alkyldiglycol nitrates, for example C 1 -C 10 alkyl nitrates, especially primary amyl nitrate, cyclohexyl nitrate, isooctyl nitrate or ethyldiglycol nitrate (see Ullmanns Encyclopedia of Technology). Chemie, 4th edition, Volume 12, page 577) or, where appropriate, mixtures of these nitrates with each other or with hydrocarbons. Hydrocarbons which may be mentioned are aliphatic and aromatic distillates, both pure solvents and cross-sections, for example aliphatic-based (n- and iso-alkanes), as well as aromatic or reformate fractions having viscosities up to about 50.degree. 2 mm 2 / s, in particular kerosene having, for example, a boiling range of 180 to 210 ° C. or the commercial Shell Sol product of Shell AG The content of the additives for improving the fluidity according to the invention in polymers PFP grafting, based on the solvent system, is usually in the

range of 30 to 80% by weight.

  The base polymer b) is a copolymer of ethylene and vinyl acetate (EVA) which may furthermore contain a third monomer component (terpolymer) with a vinyl acetate content of 28 to 40% by weight and preferably from 28 to 35% by weight. For example, other olefins generally substituted in the range of from 3 to 50 carbon atoms, especially from 3 to 10 carbon atoms per unit of olefin, in particular dienes, such as, for example, isobutylene and diisobutylene. Advantageously, the EVA copolymers have a relatively low molecular weight Mn, for example in the range from 400 to 10,000, in particular from 500 to 5,000 [determined by osmometry, and especially by osmometry in

  gas phase <cf. R. Vieweg and D. Braun, Kunststoff-

  Handbuch, Volume I, Carl Hanser-Verlag, Munich 1975, pp. 328-341) or by gel chromatography or exclusion chromatography (see Ullmanns Encyclopedia of Technische Chemie, 4th edition, Volume 5, Verlag

Chemie 1980, pp. 166-171>.

  As the viscosity of the EVA copolymers (according to DIN 1342, DIN 51 562 and DIN 7745) at 25.degree. C. in xylene, values of 6 to 30 ml / g, in particular from 10 to 20 ml. / g proved to be appropriate. In addition, a defined degree of branching appears to be important. The degree of branching is preferably 3-15, in particular 6-9 CH 3 groups per 100 CH 2 groups. Its determination is carried out in a known manner by H NMR spectroscopy. The preparation of the copolymers b) is known per se:

  for example, according to the DE-patents

  For example, the preparation is advantageously carried out by copolymerization of the monomers in the autoclave at temperatures of 80 ° C. to 150 ° C. and at pressures of 80.degree. 5 to MPa, in the presence of free-radical initiators, such as, for example, peroxides and in solvents

inert organic substances.

  Usable types exist for example in commerce. In general, the grafting of the components defined in a) on the base polymer b) is carried out based on known grafting processes. Regarding the details of the preparation of graft copolymers, reference will be made to the corresponding literature, for example Houben-Weyl, Methoden der

  Org. Chemie, 14/1, pp. 110 sq. Block Copolymers, D.C.

  Allport, W.H. Janes, Appl. Sci. Publishers Ltd., London 1973; Graft Copolymers, H.A.I. Battaerd, G.W. Tregear, Polymer Reviews, vol. 16 (1967); Block and Graft Polymers, W. J. Burlant, A.S. Hofmann, Reinhold Publishers

Corp., New York, 1960.

  By definition, it concerns, with regard to the monomers of the grafting components a), alkyl esters of methacrylic acid having 8 to 15 carbon atoms, in particular 10 to 15 carbon atoms in the alkyl radical. , isoalkyl radicals

  being as useful as n-alkyl radicals.

  We will mention in particular the methacrylates of iso-

  C10 alkyl, whereas n-alkyl methacrylate in CA0 is not quite so suitable. On the other hand, mention will be made particularly of C 12 -C 14 alkyl methacrylates. The monomers can be

also grafted in mixture.

  The weight ratio of the graft component a) to the base polymer b) is preferably from 1: 4 to 4: 1, in particular from 1: 1 to 3: 1. We will mention the ratios 1 <+ l>: 1. In this case, it is possible to proceed as follows: advantageously, the base polymer, for example EVA or an ethylene / vinyl acetate / diisobutylene terpolymer, is introduced beforehand into a suitable polymerization vessel and is dissolved in LM solvent, for example in kerosene. The amount of LX solvent used obviously depends, to a certain extent, on the nature of it. If kerosene is used, it can for example be based, as a driving rule, on a ratio by weight of the base polymer b) to the solvent LM of 1: 1. We obtain

  then - depending on the amount of graft polymer -

  polymer contents of more than 65% by weight as a rule. The dissolution is advantageously assisted by heating with stirring, for example at 90 ° C. Then, preferably at elevated temperature, but taking into account the decomposition temperatures of the initiators used, for example up to 90 ° C, and under an atmosphere of a protective gas such as nitrogen or argon, the monomers and an initiator, for example in a mixture, advantageously using a dosing pump and over a period of time, for example 2 1/2 hours. Suitable initiators are the usual radical initiators per se, in particular "per" compounds such as peresters, for example tertiary butyl peroctanoate. In general, the amount of initiator added is in the range of 0.5 to 5% by weight, preferably 1 to 4% by weight, based on the monomers. Advantageously, a further quantity of initiator is added at the end of the addition, for example about 15% by weight of the quantity already introduced. As the total duration of the polymerization, it can generally be set as indicative over a period of about 8 to 16 hours. As a general rule, any homopolymer formed during the polymerization of a) can remain in the feedstock, which can thus be used as such, that is to say without

special purification.

  The fluidity-improving additives represent, according to the invention, relatively concentrated polymer solutions having a content of PFP-grafted polymers.

  between 30 and 80% by weight in the LX solvents.

  They are advantageously added to the oils or fractions whose fluidity must be improved so that they contain 10 to 1000 ppm, preferably 50 to 300 ppm of PFP graft polymer. The action of additives improving the fluidity is manifested above all

  marked with middle distillates (see above).

  In addition to the additives improving the fluidity according to the invention, it is also possible to add to the fractions other adjuvants known per se, such as antioxidants, emulsifiers, as well as other additives. We

  mention in particular the addition of anti-

fouling of the injectors.

  The additives improving the fluidity according to the invention are characterized by a remarkable action with relatively small added quantities. In the case of middle distillates, a reduction in the freezing point and filterability of these substrates is achieved.

at 30 ° C on average.

  The following examples are intended to illustrate the invention. The determination of the effective viscosity () is carried out on the rotational viscometer according to DIN 53 018. The determination of the limiting viscosity is carried out as defined in DIN 1342 or IZOD 1628-6. The clogging point of the cold filter (CFPP) is determined in accordance with DIN 51 428 [cf. also Journal of the Institute of Petroleum, vol. 52 (510), pp. 173185

26 8792

  (1966)]. It indicates the limit value of the filterability.

  The pour point (lowest temperature at which a mineral oil or a mineral oil distillate flows just yet) is determined according to DIN 51 597 or ASTX D-97, for Point Test. Exemriles. All the ethylene / vinyl acetate copolymers and terpolymers used in the following examples have a degree of branching of between 3 and 15 CH 3 groups.

per 100 CH2 groups.

  A. Preparation of PFP graft polymers

Example 1

  In a round bottom flask equipped with a sickle-shaped stirrer and a reflux condenser, 750 g of an ethylene / vinyl acetate / diisobutylene terpolymer [61:28:11; limiting viscosity (xylene, 25 ° C.) = 16 ml / g] are dissolved in 750 g of kerosene by stirring at a temperature of 90 ° C. A mixture of 750 g of isoalkyl methacrylate and 11.25 g of tertiary butyl peroctanoate is then added to the previously introduced solution under a nitrogen atmosphere.

  the space of 2 hours, by means of a dosing pump and at 90 C.

  After the end of the addition, another 1.5 g of tertiary butyl peroctanoate is added. The total polymerization time is 16 hours. The product contains 67% of polymer, it is fluid to

  the ambient temperature [f, f. (25 ° C) = 2600 mPa.s;

  (40 ° C) = 890 mPa.s] and is whitish cloudy. The

  solidification point is at -10 ° C.

  EXAMPLE 2 The procedure is analogous to Example 1, but to the solution of the ethylene / vinyl acetate / diisobutylene terpolymer is added 1500 g of isoalkyl methacrylate and 22.5 g of butyl peroctanoate. in the space of 2 hours. ll The product contains 75% of polymer, it is fluid to

  room temperature [., f. (25 ° C) = 9600 mPa.s; yf ,.

  (40 ° C) = 2700 mPa.s] and is whitish cloudy. The

  solidification point is + 3'C.

Ee = the

  The procedure is as described in Example 2.

  However, 750 g of an ethylene / vinyl acetate copolymer are dissolved (AV content = 32% by weight, limiting viscosity).

  (xylene, 25 ° C) = 18.9 ml / g] in 750 g of kerosene.

  The product contains 75% by weight of polymer, is fluid at room temperature (22 ° C) (f = 36,500 mPa.s) and is whitish cloudy. Point of

solidification is + 4'C.

Examples 4 to 8

  The execution of the preparation process is carried out as described in Example 2. In each case, a different methacrylate is added to the copolymer.

  ethylene / vinyl acetate, in the ratio by weight 1: 2.

  Example Methacrylate Viscosity Content Polymer Aspect Point Solidification 4 C12-1, -MA 75% 17,800 -2'C Unbranched whitlow bloom% C, 2

J5% C ,.

  5 Iso-CIo-MA + 75X 56,000 + 5'C Bleaching disorder

2-dimethylamino

  ethyl-MA = 90 + 10 6 n-Clo-MA 75% 17,700 + 4'C Whitening disorder 7 IsoCi3-A 75% 46,600 + S'C Whitish disorder 8 C12-1a-MA 75% 5,800 +2 ' C. 60% branched whitish disorder B. Effect of improving fluidity The fluidity improving additives prepared in Examples 1-8 are added to a series of products within the range of middle distillates. The products designated DK1 to DK7 are as follows: DK1 denotes the Texaco fuel oil product EL DK2 denotes the Gulf Diesel fuel product DK3 denotes the product of the Lindsay Refinery Typ G1W2 DK4 denotes the product GiW3 DK5 denotes the Ethyl BSO product Fuel DK6 denotes the product BP D 12

  DK7 denotes the G2W4 product of the Lindsay Refinery.

  CFPP middle distillates wire H o s- (nf t-4

  DKI (4.2) * DK2 (-2) * DK 3 (-7) * DK 4 (-7) * DK 5 (-8) * DK 6 (-3) * DK 7 (-4) *

  Ex ante 37, 50 6 5 1o 65 100 i zo 100 133 200 100 133 2 00 t33 200o 50 67 -o 100 1) 32 t N. or

NO. as regards -Ir

o

  ## EQU1 ## 17 11-12 -223-11 14 9 -6 <-4 O

  c: <. OC.f (D, 0 c EVA 2 -9 -12 -13 -le -il -14 -21-11 -14 r) CD o it according to ex.I l l z 2 1 l 1 l 1 1 1 O

  12 1 O 2 -13-17 -22 -13 -18 -19 -13 -19 -17 -10 H1 H1

13 12 c.c 2

l-, el- c-t-

  14 4m, -14-16 -1Il1 -15 Z-c (Dct c: 16 cold 6 - () -17 d i () 1

C <D C

  It, TBLA i_ <o * The values in parentheses give the clogging point of the cold filter (CPP) without addition of additive (in OC) C r \, Cold gold (CFPP <o o 'O

Claims (6)

  1.- polymeric fluidity improving additives for middle distillates, based on grafted ethylene / vinyl acetate copolymers as a component of a solvent system, characterized in that, as an agent for the improvement of fluidity, PFP graft polymers consisting of: a) 20-80% by weight of methacrylic acid esters and C 6 -C 18 alkanols, and b> 80-20% by weight of copolymers ethylene / vinyl acetate, the viscosity of non-grafted ethylene / vinyl acetate copolymers (measured at 25 ° C. in xylene) being between 6 and 50 ml / g and the degree of branching being between S and CH 3 groups per 100 CH 2 groups, in an LX solvent having a boiling point of at least  C under a pressure of 1.02 bar.   2.- fluidity-improving polymer additives according to claim 1, characterized in that the ethylene / vinyl acetate copolymer defined in b) has a content of   vinyl acetate 28 to 40% by weight.   3.- fluidity-improving polymer additives according to claim 1, characterized in that the initial viscosity of the ethylene / vinyl acetate copolymers t9 spec / c, measured at 25 ° C in xylene, is between 6 and 30 ml / g.   4.- Polymer additives improving fluidity according to   any of claims 1 to 3, characterized   in that component a) consists of esters of   methacrylic acid with C 1 -C 9 alkanols.   5.- Polymer additives improving fluidity according to   any of claims 1 to 4, characterized   in that component a) consists of the ester of   acrylic acid with the iso-alkanol C0o.   6.- Polymer additives improving fluidity according to   any of claims 1 to 5, characterized   in that the weight ratio of the grafted component a) to the base polymer b) is between 1: 4 and 4: 1, 7. -Fluidity-improving polymer additives according to claim 6, characterized in that the ratio by weight of the graft component a) to the base polymer b) is between 1: 1 and 3: 1.